US says Covaxin successfully neutralises Delta variant

India's Covaxin, developed by Bharat Biotech in collaboration with the Indian Council of Medical Research, effectively neutralises both Alpha and Delta variants of coronavirus, the United States' National Institute of Health (NIH) has said.

The NIH said results of two studies of blood serum from people who had received Covaxin suggest that the vaccine generates antibodies that effectively neutralise the B.1.1.7 (Alpha) and B.1.617 (Delta) variants of SARS-CoV-2, first identified in the United Kingdom and India, respectively.

The top American health research institute, which has a history of strong scientific collaboration with India, also said that an adjuvant developed with funding from it has contributed to the success of the highly efficacious Covaxin, which has been administered to roughly 25 million people till date in India and elsewhere.

Adjuvants are substances formulated as part of a vaccine to boost immune responses and enhance a vaccine's effectiveness.

Covaxin comprises a disabled form of SARS-CoV-2 that cannot replicate but still stimulates the immune system to make antibodies against the virus.

Published results from a phase 2 trial of the vaccine indicate that it is safe and well tolerated, the NIH said, adding that safety data from a phase 3 trial of Covaxin will become available later this year.

'Meanwhile, unpublished interim results from the phase 3 trial indicate that the vaccine has 78 per cent efficacy against symptomatic disease, 100 per cent efficacy against severe COVID-19, including hospitalisation, and 70 per cent efficacy against asymptomatic infection with SARS-CoV-2, the virus that causes COVID-19,' it said.

'The results from two studies of blood serum from people who had received Covaxin suggest that the vaccine generates antibodies that effectively neutralise the B.1.1.7 (Alpha) and B.1.617 (Delta) variants of SARS-CoV-2, first identified in the UK and India, respectively,' the NIH said.

Ending a global pandemic requires a global response, said Anthony S Fauci, director of the National Institute of Allergy and Infectious Diseases (NIAID), part of NIH.

"I am pleased that a novel vaccine adjuvant developed in the US with NIAID support is part of an efficacious COVID-19 vaccine available to people in India," he said.

The adjuvant used in Covaxin, Alhydroxiquim-II, was discovered and tested in a laboratory by the biotech company ViroVax LLC of Lawrence, Kansas with support from the NIAID Adjuvant Development Program.

Alhydroxiquim-II is the first adjuvant in an authorised vaccine against an infectious disease to activate receptors TLR7 and TLR8 that play a vital role in the immune response to viruses.

In addition, the alum in Alhydroxiquim-II stimulates the immune system to search for an invading pathogen. Molecules that activate TLR receptors stimulate the immune system powerfully, but the side effects of Alhydroxiquim-II are mild, the NIH said.

According to the NIH, the NIAID Adjuvant Program has supported the research of the founder and chief executive officer of ViroVax, Sunil David, MD, PhD, since 2009.

His work has focused on searching for novel molecules that activate innate immune receptors and developing them as vaccine adjuvants.

The collaboration between Dr David and Bharat Biotech International Ltd. of Hyderabad was initiated during a 2019 meeting in India coordinated by the NIAID Office of Global Research under the auspices of NIAID's Indo-US Vaccine Action Program.

A delegation of five NIAID-funded adjuvant investigators, including Dr David; two members of the NIAID Division of Allergy, Immunology, and Transplantation; and the NIAID India representative, visited four leading biotechnology companies to learn about their work and discuss potential collaborations.

The delegation also attended a consultation in New Delhi co-organised by NIAID and India's Department of Biotechnology and hosted by India's National Institute of Immunology.

Among the scientific collaborations sparked by these activities, Bharat Biotech signed a licensing agreement with Dr David to use Alhydroxiquim-II in their candidate vaccines.

This license was expanded during the COVID-19 pandemic to include Covaxin, which has received Emergency Use Authorisation in India and more than a dozen other countries.

'The company conducted extensive safety studies of Alhydroxiquim-II and undertook the complex process of scaling up production of the adjuvant under Good Manufacturing Practice standards. Bharat Biotech expects to produce an estimated 700 million doses of Covaxin by the end of 2021,' the NIH said.